The Experts below are selected from a list of 10668 Experts worldwide ranked by ideXlab platform
Y Jiang - One of the best experts on this subject based on the ideXlab platform.
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mass transfer performance comparison of two commonly used liquid desiccants libr and licl aqueous solutions
Energy Conversion and Management, 2011Co-Authors: X Q Yi, Y JiangAbstract:Abstract Mass transfer performance of two commonly used liquid desiccants, LiBr aqueous solution and LiCl aqueous solution, is compared in this paper on the basis of the same solution temperature and surface vapor pressure. According to the analysis of the analytical solutions of Heat and mass transfer processes, the key performance influencing factors are Heat Capacity Ratio of air to desiccant m * and mass transfer unit NTU m . The Heat capacities of the two liquid desiccants are about the same at same volumetric flow rate, and LiBr solution has higher density and smaller specific Heat Capacity. The variance of mass transfer unit with different operating conditions and liquid desiccants are derived based on the experimental results. In the condition of the same desiccant mass flow rate, the dehumidification performance of LiCl solution is better, and the regeneRation performance of LiBr solution is a little better or almost the same as that of LiCl solution. In the condition of the same desiccant volumetric flow rate, the dehumidification performance of LiCl solution is a little better or about the same compared with LiBr solution, and the regeneRation performance of LiBr solution is better. The COPs of the liquid desiccant systems using these two desiccants are similar; while LiCl solution costs 18% lower than LiBr solution at current Chinese price.
H Hegab - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of thermal model of parallel flow microchannel Heat exchangers subjected to external Heat flux
International Journal of Heat and Mass Transfer, 2012Co-Authors: Bobby Mathew, H HegabAbstract:Abstract This communication documents the experimental investigation of the theoretical model for predicting the thermal performance of parallel flow microchannel Heat exchangers subjected to external Heat flux. The thermal model investigated in this communication is that previously developed by the authors of this communication; Mathew and Hegab [B. Mathew, H. Hegab, Application of effectiveness-NTU relationship to parallel flowmicrochannel Heat exchangers subjected to external Heat transfer, International Journal of Thermal Sciences 31 (2010) 76–85]. The validity of the theoretical model with respect to microchannel profile, hydraulic diameter, Heat Capacity Ratio and degree of external Heat transfer is checked. The microchannel profiles investigated are trapezoidal and triangular with hydraulic diameter of 278.5 and 279.5 μm, respectively. The influence of hydraulic diameter is analyzed using trapezoidal microchannels with hydraulic diameters of 231 and 278.5 μm. Experiments are conducted for Heat Capacity Ratios of unity and 0.5 using the Heat exchanger employing the trapezoidal microchannel with hydraulic diameter of 278.5 μm for purposes of validating the model. Experiments are done for all Heat exchangers for two different levels of external Heat transfer; 15% and 30% of the maximum possible Heat transfer. Irrespective of the parameter that is investigated the experimental data are found to perfectly match with the theoretical predictions thereby validating the thermal model investigated in this communication.
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application of effectiveness ntu relationship to parallel flow microchannel Heat exchangers subjected to external Heat transfer
International Journal of Thermal Sciences, 2010Co-Authors: Bobby Mathew, H HegabAbstract:In this paper the thermal performance of parallel flow microchannel Heat exchangers subjected to constant external Heat transfer has been theoretically analyzed. Equations for predicting the axial temperatures as well as the effectiveness of the fluids of a microchannel Heat exchanger operating under laminar flow conditions have been developed. In addition, an equation for determining the Heat transfer between the fluids has also been formulated. Irrespective of the Heat Capacity Ratio, for a specific NTU, external Heating always decreases and increases the effectiveness of the hot and cold fluid, respectively. The opposite trend in the effectiveness of the fluids is observed when they are subjected to external cooling. Moreover, under unbalanced flow conditions (Heat capacities of two fluids are not equal) the effectiveness of the fluids depended on the fluid with the lowest Heat Capacity. Among the two unbalanced flow conditions (Heat capacities of the two fluids are not equal) the effectiveness of the fluids is greatest when the hot fluid has the lowest Heat Capacity. At a given NTU, reduction in Heat Capacity Ratio improved the effectiveness of the fluids. Under certain operating conditions temperature cross over was observed in the Heat exchanger.
Weizong Wang - One of the best experts on this subject based on the ideXlab platform.
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thermophysical properties of high temperature reacting mixtures of carbon and water in the range 400 30 000 k and 0 1 10 atm part 1 equilibrium composition and thermodynamic properties
Plasma Chemistry and Plasma Processing, 2012Co-Authors: Anthony B. Murphy, Weizong Wang, J D Yan, Mingzhe Rong, J W Spencer, M T C FangAbstract:This paper is devoted to the calculation of the chemical equilibrium composition and thermodynamic properties of reacting mixtures of carbon and water at high temperature. Equilibrium particle concentRations and thermodynamic properties including mass density, molar weight, entropy, enthalpy and specific Heat at constant pressure, sonic velocity, and Heat Capacity Ratio are determined by the method of Gibbs free energy minimization, using species data from standard thermodynamic tables. The calculations, which assume local thermodynamic equilibrium, are performed in the temperature range from 400 to 30,000 K for pressures of 0.10, 1.0, 3.0, 5.0 and 10.0 atm. The properties of the reacting mixture are affected by the possible occurrence of solid carbon formation at low temperature, and therefore attention is paid to the influence of the carbon phase transition by comparing the results obtained with and without considering solid carbon formation. The results presented here clarify some basic chemical process and are reliable reference data for use in the simulation of plasmas in reacting carbon and water mixtures together with the need of transport coefficients computation.
Theodosios Korakianitis - One of the best experts on this subject based on the ideXlab platform.
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Natural gas fueled compression ignition engine performance and emissions maps with diesel and RME pilot fuels
Applied Thermal Engineering, 2014Co-Authors: Syahrul Imran, D. R. Emberson, D. S. Wen, Roy J. Crookes, Antonio Diez, Theodosios KorakianitisAbstract:When natural gas is port/manifold injected into a compression ignition engine, the mixture of air and the natural gas is compressed during the compression stroke of the engine. Due to the difference in the values of specific Heat Capacity Ratio between air and natural gas, the temperature and pressure at the time of pilot fuel injection are different when compared to a case where only air is compressed. Also, the presence of natural gas affects the peak in-cylinder (adiabatic flame) temperature. This significantly affects the performance as well as emissions characteristics of natural gas based dual fueling in CI engine. Natural gas has been extensively tested in a single cylinder compression ignition engine to obtain performance and emissions maps.Two pilot fuels, diesel and RME, have been used to pilot natural gas combustion. The performance of the two liquid fuels used as pilots has also been assessed and compared. Tests were conducted at 48 different operating conditions (six different speeds and eight different power output conditions for each speed) for single fueling cases. Both the diesel and RME based single fueling cases were used as baselines to compare the natural gas based dual fueling where data was collected at 36 operating conditions (six different speeds and six different power output conditions for each speed). Performance and emissions characteristics were mapped on speed vs brake power plots. The thermal efficiency values of the natural gas dual fueling were lower when compared to the respective pilot fuel based single fueling apart from the highest powers. The effect of engine speed on volumetric efficiency in case of the natural gas based dual fueling was significantly different from what was observed with the single fueling. Contours of specific NOX for diesel and RME based single fueling differ significantly when these fuels were used to pilot natural gas combustion. For both of the single fueling cases, maximum specific NOX were centered at the intersection of medium speeds and medium powers and they decrease in all directions from this region of maximum values. On the other hand, an opposite trend was observed with dual fueling cases where minimum specific NOX were observed at the center of the map and they increase in all direction from this region of minimum NOX. RME piloted specific NOX at the highest speeds were the only exception to this trend. Higher specific HC and lower specific CO2 emissions were observed in case of natural gas based dual fueling. The emissions were measured in g/MJ of engine power.
X Q Yi - One of the best experts on this subject based on the ideXlab platform.
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mass transfer performance comparison of two commonly used liquid desiccants libr and licl aqueous solutions
Energy Conversion and Management, 2011Co-Authors: X Q Yi, Y JiangAbstract:Abstract Mass transfer performance of two commonly used liquid desiccants, LiBr aqueous solution and LiCl aqueous solution, is compared in this paper on the basis of the same solution temperature and surface vapor pressure. According to the analysis of the analytical solutions of Heat and mass transfer processes, the key performance influencing factors are Heat Capacity Ratio of air to desiccant m * and mass transfer unit NTU m . The Heat capacities of the two liquid desiccants are about the same at same volumetric flow rate, and LiBr solution has higher density and smaller specific Heat Capacity. The variance of mass transfer unit with different operating conditions and liquid desiccants are derived based on the experimental results. In the condition of the same desiccant mass flow rate, the dehumidification performance of LiCl solution is better, and the regeneRation performance of LiBr solution is a little better or almost the same as that of LiCl solution. In the condition of the same desiccant volumetric flow rate, the dehumidification performance of LiCl solution is a little better or about the same compared with LiBr solution, and the regeneRation performance of LiBr solution is better. The COPs of the liquid desiccant systems using these two desiccants are similar; while LiCl solution costs 18% lower than LiBr solution at current Chinese price.
